Light-modifying attachment for lamps used in photography



May 11,

1948. H. JACOBS LIGHT-MODIFYING ATTACHMENT FOR LAMPS USED IN PHOTOGRAPHY Filed July 11, 1946 Patented May 11 1948 T cl rics. c.

EIGHT-MODIFYING ATTAGHMENTFOR LAMPS USED IN PHOTOGRAPHY hears Mews, London, England implication July 11, 1940, serial newsman In Great Britain August 28, 194-5 V V 1 I This invention relates to a light-modifying attachment for lamps used in photography. for illumina'ting' the subu'ect bl" object to be photo- Lamps for this purpose usually-comprise an electric filament lamp mounted in a bowl or hood forming a reflector.

For intense illumination, high powered electric filament lamps, usually termed fphoto-flood bulbs? are usually employ d. i

Ccilect color rendering in terms of black and white phetoguaphy requires faithful translation int monochrome of color as seenby white dayight.

The normal electric filament lamp' produces a white light which differs a p fciably from day-- light, inasmuch as although it is rich in red a'hd yellow, it is lacking in the blue and adjacent com ponents at the blue end of the s ectrum.

Even the more intensewhite lightproduced by the aforesaid photofiood hulbs failsclosely to .3 Claims. (Cl. 240-1.??? Y W I Figure 6 is a side elevation of another form of the holdezj Figure '7 is er 'fi- Figure 8 is an end view oi the clamping block by which theholdei' is attached to the rini of the reflector, and

Figure Q showstoasmaller scale and in side elevationthe holde illustrated by Figures 6 to 8 applied to e of; reflector.

In the embodiments illustrated, a clamping head I fixed on oneend of a rod 1; is employed as a holderjor one or more light modifying filters or screens am the fonn oi circular discs.

The clamping head consists of a bifurcated body, convenienty oi cylindrical form} provided a top plah View corresponding to v with a hindi-ng s r 4' to gi'ip the edge-of the light simulate daylight owing to its deficiency in the 7 blue component. I 7

An object of the invention is to provide a'simhle attachment for lamps used inphotography for illuminating purposes, whereby to effect blending, filtering and control of the light so as to obtain correct color Vahlesjn portraiture b artificial light, with all types of 'photdg'lailhic films or plates. w j 1 According to the present inventiqnya holder is provided for one or more light-modifying filters, screens or the like elements, said holder being adapted for attachment'to the reflector of a; lamp used in photo raphy for ilhiilifilafil'ig purptses', so as tc unpcit saicieiement or elements iiifil'oht of the light source to modify the'light tfansinitted from said light source to suit particular requiremeets;

According to the invention; nicrecverj the holde -may be such that its efie tive'l'ength is adjustable so that it can" be applied with equally effeet'ive'result's to reflectors of differing sizes.

In the drawings: Figure l is an elevational view the holder. g 'e I Figure 2 shows inside elevation and to a sit-1311c? of one for h of scale the holder illustrated by Figure 1 afibli ed' to.

a bowl type of reflector; w ich; is shown broken away toillustrate more clearly the mode of attachment. I I V v Figure 3 is a front elevation cotrespond'ihg to FigureZ. a Y

Figure 4 is an elevation of the top of the holder illustrated by Figure 1, showing two light-modifying screens held therein. 7 V

Figure 5 shows in elevation a modified form of the holder for use where the lamp projects to a point "on or beyond the finljflf the reflector.

modifying disc o disc s i'nsertd between the hiat e se r he ea b, v Astrip of rubber or tell; doubled upon itself is preferably inseit ed inthe head to cover the inserted edge of the disc or discs 3 ion protective p e ,s V b in the embodiment illustrated by Figures 1 to 5, the rod 2 is slidably mounted in an attaching mp s; al n, $2 ....f9mi are b ur ted' p conveniently cylindrical provided with a binding screw 1; to clamp it on to the of a liowl type reflector 8 of a lam-p employed in photography for illuminating the subject or object to be photographed. the rim being received between the loiintentions of the attaching clamp 6 as shown in Figure2.-- v

Asshown lnjigures and 3, the attaching clamp 6 is clamped on the ofthe-l'efiectol 8 at the bot-tom theroL-and with the lamp in the position illustrated; in which the optical axis A-r-A is horizontal. The 'rod- 2, which is located in a diametrical direction in relation to theiront of the reflector, is axially adjustable vertically in the attaching clamp 6; to centralize the light modifying disc or discs Scarried by the clamping head i, in relation to the lamp bulb or-reflector, a binding screw'lbeing provided in th-e attaching clampto hold thel od in the position to which it is adjusted, It will: be appreciated; however, that the attaching clamp Scan be clamped on the rim of the reflector Oat any other position around said rim to support the rod 2'50 that its axis extends in a diametrical direction in relation to the front of the reflector 8-. V j g 'I he clamping screws ;4,g'l and 9 are provided with; knurled heads to facilitate tightening and.

e i M I l The light 7 odifying-discs 3 in the present embodl e s c nsi t of we c cu d c l ar l glass and anqther of white ground glass, said discs bcing used} indcpendentlyj or together face to face, according to the effect required. I The light modifyingdiscsi are of less diainetei 3 than that of the front of the reflector 8 as they are required to cover only the central field of the lamp bulb. j 1 r In the most convenient mode'of use, the attaching clamp 6 is clamped by the screw 1 on the.

rim of the reflector 8 at the bottom, so that the rod 2 inserted in said clamp 6 is located in an up-' 7 right position, assuming the reflector to be in the f position illustrated. e The selected light-modifying disc 3, or, if required, both discs 3 face to face, are clamped at the bottom edge in the clamping head I by thebinding screw 4, and the rod 2 is adjustedaxially in the attaching clamp 6 to centralise the disc or discs 3 with the lamp bulb or reflector 8, whereupon the rod 2 is clamped in the adjusted position in the attaching clamp 6 by the binding screw 9.

The rubber or felt strip 5 covers the clamped edge of the light-modifying disc or discs 3, so affording protection against fracture in the clamping operation.

By reason of the capability of axial adjustment of the rod 2 in the attaching clamp 6, the attachment can be applied effectively to existing reflectors or hoods of known types of photographic lamps of various sizes.

To suit the known types of lamp, in which the lamp bulb approaches closely to, or projects from the front of the reflector, the rod 2 can be cranked at the end'carrying the clamping head I as shown in Figure 5, or'the clamping head I could be set forward on the rod2:

With the blue glass disc 3 alone supported, as above described, in front of the lamp bu-lb, the direct red rays are filtered out and the blue rays retained, and these blended with the indirect light reflected by the reflector produce alight which is both soft and actinic-and of a quality similar to that of daylight.

With both the blue disc and white ground glass disc supported face to face in the clamping head I in front of the lamp bulb, the light obtained is as last described, but difiused.

With the white ground glass disc alone supported in the clamping head I in front of the lamp bulb, the usual harsh quality of the light is mellowed by cutting out the hot spot only, without reducing the reflected light which is soft in character, the disc forming alight diffuser.

Asthe light-modifying disc or discs 3 cover only the central field of the reflector, adequate ventilating space is provided-and overheating is avoided. I I

In the embodiment illustrated by Figures 6 to 9, in which the same reference numerals as those in the previously described embodiments are used to denote corresponding parts, the rod 2 carrying the clamping head I is slidably mounted and held by a binding screw It] in a support I I, preferably cylindrical, which is carried by a second rod I2, provided with an attaching clamp I3 to clamp on the rim of the reflector 8, so that said rod I2 extends in the direction of the optical axis of the lamp. Y

The attaching clamp I3 is in the form of a rectangular metal block, bifurcated or notched as at I 4 to engage over the rim of the reflector on which it is clamped by a binding screw I5.

The rod I2 is slidably mounted'in the attaching clamp I3 so that it can be adjusted axially therein, and a binding screw I6 is provided in said clamp I2 to'clamp the rod I2 in its adjusted position therein.

As shown more clearly in Figure 8, the bore I! for the rod I2 is off-set to one side of the middle of the clamp I3, and the clamping screw I4 is positioned to the other side; 4 By means of'the rod I2, the light modifying disc or discs 3 mounted in the clamping head I can be adjusted forwards and backwards in front of the lamp in the direction of the optical axis of the lamp besides being adjustable in the diametrical direction of the lamp by the rod 2.

The rod I2'is connected to the support ID for the rod 2by a pivotal joint I8, which provides also for angular adjustment of the light modifying disc or discs mounted in the clamping head I, as indicated diagrammatically by the dotted lines in Figure 9, such angular adjustment of the light modifying disc or discs providing for partial diffusion;

In the embodiment illustrated, a plain pivotal joint I8 with a pivot pin I9 is shown, but a ball and socket joint can be used, so providing for universal adjustment of the light modifying screens 3 mounted in the clamping head I.

With the attachin clamp I3 clamped to the rim of the reflector 8 at the bottom and the rod 2 set at right angles to the rod I2, as shown in Figure 9, then assuming the lamp is in the position illustrated in that figure, in which the optical axis A-A of the bulb or reflector is horizontal, the light-modifying disc or discs 3 mounted in the clamping head I can be adjusted in a vertical direction by the rod 2, and in a horizontal direction by the rod I2 the joint I8 providing for any angular adjustment that may be required.

The attachment in any of the embodiments described with' its light-modifying discs 3 avoids undue contrast effects in the photograph made; also, it does not bring about the unnatural strained expression of the sitter usually prevailing under the glare of uncovered lamps and, moreover, it presents a neat appearance and avoids the unpleasant odors of scorching and overheating ofthe reflector incidental to the use of muslin or like screens as frequently provided heretofore to cover the entire front of the reflector for difiusing purposes.

The invention is not restricted to the particular embodiments described by way of example.

I claim:

1. A light-modifying screen holder for application to a reflector of a'lamp used in taking photographs by artificial light, comprising a bifurcated head with a binding screw for selective and edge reception between the bifurcations and clamping by said screw of light-modifying screens, a rod having one end attached to said bifurcated head, and abifurcated attaching element with a binding screw for clamping it on to the rim of the reflector, said attaching element having a transverse bore for the slidable reception of said rod and anotherclamping screw for clamping said rod in said bore to position such of said light-modifying screens as are clamped in said bifurcated head in front of the lamp.

'2'. A light-modifying screen holder for application to a reflector of a lamp used in taking photographs by artificial light, comprising a bifurcated holding clamp with a binding screw for the selective reception between the bifurcations and clamping by the binding screw of light-modifying screens, a rod carrying said bifurcated clamp, a holding for saidrod, said holder providing for axial adjustment of said rod therein, a binding screw for clamping said rod in said holder, a bifurcated attaching clamp with a binding screw for clamping it on the reflector rim, a

second rod slidable axially in said attaching clamp towards and away from the reflector, a binding screw for clamping said second rod in said attaching clamp, and a pivotal joint between'said second rod and said holder for the first rod to set such of said light-modifying screens as are mounted in said holding clamp at an angularly adjustable position in front of the lamp. I

3. A light-modifying screen holder for application to a reflector of a lamp used in taking photographs by artificial light, comprising two rods connected together at right-angles to one another, a screw clamp on the end of one of said rods for selective reception and edge clamping therein of light-modifying screens and a clamp on the end of the other rod for clamping it to the reflector rim to extend therefrom in the direction of the optical axis of the lamp and support the first mentioned rod in the diametrical direction of the reflector with such of said lightmodifying screens as are clamped in said clamp on said first mentioned rod in front of the lamp,

each of said rods being axially adjustable;

HENRY JACOBS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

